Question

A charge of $+2 \mu C$ is placed at $x =0$ and a charge of $32 \mu C$ at $x =60 cm$. A third charge $Q$ is placed on the $x$-axis, such that it experiences no force. The distance of the point from $+2 \mu C$ is (in $cm$ )

• A. 12
• B. 20
• C. 15
• D. 10

Answer 1

Answer: (A)

The coulombic ferce is ginen by:- $F=\frac{q_{1} q_{2}}{4 \pi \text { tor }^{2}}$ $r \rightarrow$ Dixtance of separati en
$q_{1}, q_{2} \rightarrow$ Magnitude of the two charges
to $\rightarrow$ Permittivity of free spare.
Let charge $Q$ be placed at a distavce ' $x$ ' from $2 \mu C$ charge such that it experiences no force.
$
\begin{array}{c}
\therefore \frac{2 \times 10^{-6} \times Q}{4 \pi \text { to }^{2}}=\frac{32 \times 10^{-6} \times Q}{4 \pi \text { fo }_{0}(0.6-x)^{2}} \\
\text { or, } 16 x^{2}=(0.6-x)^{2} \\
\text { or, } 4 x=0.6-x \\
\therefore x=0.12 m \\
\therefore x=12 cm
\end{array}
$